Variability between silver thiosulfate and 1-naphthaleneacetic acid applications in prolonging bract longevity of potted bougainvillea

Potted bougainvillea 'Purple Flower' and 'Taipei Red' in four different sta ges of bract development were sprayed with STS (0.1, 0.5 mM) or NAA (25, 50 ppm) and were moved to low-light indoor conditions after treatment. The ex periment was conducted twice, and the results showed that 0.5 mM STS and NA A (25, 50 ppm) could significantly prolong the longevity of bracts at certa in stages in both cultivars. Treatment with 0.1 mM STS, however, had no eff ect on bract longevity of 'Taipei Red' at any stage. The prolonging effect of STS was more obvious in early bract stages and decreased as the bract st age increased, whereas NAA applications at later bract stages produced bett er results on prolonging bract longevity. The ethylene production rates of bracts in these two cultivars were higher in early stages and gradually dec reased with bract growth. We propose that this phenomenon is related to the variability between STS and NAA in prolonging bract longevity of bougainvi llea. (C) 2001 Elsevier Science B.V, All rights reserved.